The present disclosure relates generally to electrochemical double layer capacitors, and more particularly to cell and package designs to facilitate high energy density output from an EDLC.
Energy storage devices such as electrochemical double layer capacitors (EDLCs), which are also referred to as ultracapacitors or supercapacitors, may be used in a variety of applications where a discrete power pulse is required. Such applications range from cell phones to hybrid vehicles. Ultracapacitors can include two or more carbon-based electrodes separated by a porous separator and an organic electrolyte. The foregoing active components, which define an electrode set, can be arranged in a variety of configurations. Example configurations include parallel plate and jelly roll designs. In use, the active components are contained within a housing or package.
Important characteristics of an ultracapacitor are the energy density and the power density that it can provide. The energy density and the power density are largely determined by the properties of the active components. A further important characteristic is cost. Factors that impact the cost of the device include the cost of the raw materials, as well as the direct and indirect costs of the associated packaging, which can impact performance, manufacturability and reliability. It is desirable to make an ultracapacitor package simple and inexpensive while simultaneously robust and efficient.
One aspect of an ultracapacitor package is the efficiency with which the available volume is used to provide the desired energy. By minimizing unused volume within the package, the volumetric energy density of the device can be increased. In view of the foregoing, there is a need for efficient, economical and robust ultracapacitor cell and package designs.